Rotary impact wrench mechanism



Sept. 11, 1962 J. A; w. MADSEN 3,053,360

ROTARY IMPACT WRENCH MECHANISM Filed Dec. 30, 1960 3 Sheets-Sheet 2 NV EN TOR.

I .Jkns 14122 W Madsen Sept. 11, 1962 Filed Dec. 30, 1960 J. A. W. MADSEN ROTARY IMPACT WRENCH MECHANISM 3 Sheets-Sheet 3 INVENTOR. JnsAxeZ WI Madselz itcd States Pater 3,053,360 RDTARY IMPACT WRENCH MECHANISM Jens Axel W. Matisen, Sioux City, Iowa, assignor to Albertson & Company, Inc., Sioux City, Iowa, a corporation of Iowa Filed Dec. 30, 1960, Ser. No. 79,751 13 Claims. (Cl. 192-305) This invention relates generally to rotary impact tools and more particularly to improvements in impact, mechanisms and clutch means used in such tools.

The present invention finds particular utility in the general class of rotary impact tools set out and described in my prior Patent No. 2,886,997, issued May 19, 1959, and entitled Rotary Impact Wrench Mechanism. Impact wrenches as typified in that patent include rotatable impact mechanisms which function automatically and periodically to deliver a series of impact blows to a rotatable driven anvil member thereby to instantaneously deliver torque impulses to the driven member. Such torque delivery, by virtue of the mass and operational movement of the impact mechanism, markedly increases the normal torque output of the driven anvil member. Typically, such torque mechanisms or wrenches may be utilized to mount a threaded nut or like fastener element onto a threaded bolt or the like in response to the driving action of the rotatable anvil member. In such an operation the anvil member and the fastener element are rotated with and by the impact mechanism in a substantially continuous manner until such time as the advancing movement of the fastener element is sufficiently opposed to cause an effective relative movement between the impact mechanism and the anvil member which it drives. When this condition occurs, the impact mechanism operates to deliver a series of rapid sharp blows to the driven anvil member, which effectively increases torque transmission to the threaded member to drive or advance the same against the encountered load or resistance. Thus the impact mechanism in such an impact wrench serves the dual purpose of rotatably driving the driven anvil member therewith under normal torque load conditions, and thereafter intermittently impacting the anvil member with a series of blows to increase its effective torque transmission or output.

In my prior co-pending application Serial No. 55,664, filed September 13, 1960, and entitled Rotary Impact Mechanism, I revealed certain improvements in rotary impact mechanisms which included a novel cam-clutch means for accomplishing the foregoing dual purpose operation, namely the rotary driving of the anvil or rotatable driven member and the impact driving thereof when such is resisted in its rotary movements by a predetermined torque load. That improved clutch means briefly served to intermittently axially motivate a hammer means into a position of interfering engagement with portions of a rotatable driven member or anvil means with preselected variable frequency according to preselected operating characteristics of a rotary cam and ball follower arrangement. The present invention is directed generally to improvements in a rotary impact mechanism of the type set forth in my above referred to co-pending application Serial No. 55,664, and more specifically concerns improvements in the driving cam-clutch means of that mechanism.

In brief, the present invention is directed to improved driving cam-clutch means operable with preselected intervals of variable frequency to axially reciprocate a rotatably driven hammer means into positions for impacting a rotatable driven anvil member. The improved cam-clutch means of this invention therefore lends itself to an impact mechanism for periodically delivering torque between rotatable driving and driven elements; the driving element being subjected to rapid acceleration and deceleration forces. By virtue of the improved features therein, driving energy of the rotatable driving means is intermittently released to the driven anvil means with positive assurance of proper phase orientation between moving parts. Thus improved dependability of the impact mechanism to deliver impact blows to the rotatable driven member is provided by this invention.

The main object of this invention is to provide a new and improved impact mechanism for use in rotary impact tools.

Another object of this invention is to provide an improved rotary clutch means for an impact mechanism characterized by improved dependability and versatility of operation.

A still further object of this invention is to provide an improved rotary impact mechanism embodying improved rotary cam-clutch means which periodically operate to move a hammer means into a position of inter fering engagement with a rotatable driven anvil in a rotary impact tool.

Another important object of this invention is to provide a new and improved clutch means in a rotary impact mechanism for intermittently reciprocating a rotating hammer means into and out of positions of contacting interference with an adjacent rotatable driven anvil means at preselected frequency and to include rotatable cam means for varying such frequency of impact and which are operable independently of direction of rotation.

A still further object of this invention is to provide a new and improved cam-clutch means in a rotary impact mechanism for a rotary impact tool which is featured by an inherent releationship of elements capable of maintaining proper operational phase relationship between moving elements, particularly the reciprocating hammer means and the rotatable driven anvil means of a rotary impact mechanism.

A still further important object of this invention is to provide a new and improved reversible rotary camclutch means for use in a rotary impact mechanism which incorporates improved means and a simplified arrangement of parts productive of improved operational dependability, particularly as it relates to the maintenance of proper phase relationship between operating elements of the impact mechanism and which dependability is enhanced with normal operating wear of such elements.

Another important object of this invention is to provide new and improved rotary cam-clutch means operable for moving a rotating hammer mass into contact with a relatively stationary anvil whereby kinetic energy of the rotating hammer mass may be instantaneously delivered to said anvil with preselected frequency and regardless of the direction of rotation of the hammer mass.

The above and further objects, features and advantages of the present invention will appear from time to time in the following description of the preferred embodiment thereof illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a cross-sectional assembly view of a preferred form of impact mechanism embodying my present invention, with portions thereof in full elevation and indicating in dotted lines a typical supporting housing therefor;

FLIG. 2 is a partial cross-sectional view with portions thereof in elevation, showing the improved impact mechanism of this invention divorced from its housing, and

illustrating the relationship of its several elemental portions in operating relationship to deliver an impact blow; FIG. 3 is an exploded perspective showing of the major elemental portions embodied in the improved impact mechanism set out in FIG. 2 and illustrating in particular the relationship of assembly for such elements;

FIGS. 4 and 5 are plan views of opposing cam elements employed in the improved impact mechanism of this invention; the cam track portions of such elements having single lifting nodes;

FIG. 6 is a plan view, similar to FIG. 4, of a modified cam element having a pair of cam track portions and a pair of lifting nodes;

FIG. 7 is apartial perspective showing of the improved impact mechanism of this invention, showing the same substantially at the start of an operational cycle for delivering an impact blow;

FIG. 8 is an enlarged developed partial cross-sectional showing of the cooperating cam-clutch elements employed in the impact mechanism of this invention, and illustrating the relationship of such cam elements according to the FIG. 7 operational condition for the mechanism;

FIG. 9 is another perspective view, similar to FIG. 7, showing the improved impact mechanism of this invention substantially midway in its operational cycle for delivering an impact blow;

FIG. 10 is an enlarged developed partial cross-sectional view of the cam-clutch elements seen in FIG. 8, showing their relative positioning for the operating condition of the impact mechanism illustrated in FIG. 9;

FIG. 11 is another perspective view of the impact mechanism seen in FIGS. 7 and 9, showing the same conditioned for delivering an impact blow;

FIG. 12 is another partial developed cross-sectional view of the cam elements illustrated in FIGS. 8 and 10, to show their positioning at the point of delivering an impact blow according to the operating condition of the impact mechanism illustrated in FIG. 11; and

FIG. 13 is still another cross-sectional view of the cam elements seen in FIGS. 8, l0 and 12, but showing the same in return position, immediately after the delivery of an impact blow, ready for another operational cycle of the impact mechanism.

Turning now to the particular embodiment of the present invention as illustrated in the drawings, the improved impact mechanism, indicated generally at 15 in FIG. 1, is shown associated with other elements in an air-driven impact Wrench 16. Wrench 16 preferably embodies an air-operated prime mover or motor 17 enclosed by and mounted in a suitable housing 18, as indicated in dotted lines in FIG. 1. Motor 17 rotatably drives a single drive shaft 19 formed with a splined end portion 20 for driving connection with the improved impact mechanism 15. The housing 18 also supports and encloses the improved impact mechanism 15 which rotatably drives an anvil means 21 having a generally elongate cylindrical body which extends outwardly of the forward end of housing 18 and is rotatably supported by a suitable sleeve bearing means or the like (not shown) carried by the housing 18.

The anvil means 21 has its outer end portion, i.e., that portion which projects beyond the forward end of housing 18, polygonally formed with suitable planar surfaces 22 to present a polygonal male fitting portion for engaging and carrying various removable tools or implements, such as a Wrench socket formed with an appropriately mating female socket according to known practice. The opposite end of anvil means 21 is formed with a pair of radially outwardly extending and diametrically opposite rectangular arm portions 23, 23, each formed with a wedge-shaped or arcuate striking anvil segment 24 on its undersurface. Segments 24 importantly embody radially divergent end faces 25, 25 for receiving torsional impact or blows from the impact mechanism 15.

The impact wrench 16 as typified in the drawing FIG. 1 characteristically includes a pistol grip handle at one end of its protective outer housing 18 and embodies suitable fittings (not shown) for connecting the prime mover or air motor 17 thereof with a source of pressurized air. Control valves (not shown) are also typically included in such an impact wrench to regulate, shut off, and reverse the flow of air to the prime mover 17, according to recognized practice.

In their assembled relationship the prime mover 17 and particularly the shaft 19 driven thereby are aligned coaxially with the impact mechanism 15 and the anvil means 21; the shaft 19 being driven directly by the air motor 17 to directly drive and rotate the impact mechanism 15.

Shaft 19, as shown in FIG. 1, is supported in a suitable anti-friction bearing assembly or means 26 carried by a concentrically surrounding support frame or cage portion 27 fixed to and carried by internal supporting wall portions or partitioning of the housing 18. Indirect connection between shaft 19 and the anvil 21 for rotatably driving the latter is via the impact mechanism 15, which generally embodies a rotatable hammer mass or frame 30 driven directly with and by shaft 19, a hammer means 31, a cam-clutch assembly or means 32, and a central axial spindle means 33. These elemental portions of the impact mechanism serve to deliver kinetic energy from the rotatable drive shaft 19 of the air motor to the rotatably driven anvil means 21; such driving of the anvil means causing the latter to rotate normally with the impact mechanism and drive shaft 19 until the anvil means engages or is opposed by a sufficient torque load to arrest the same and cause relative rotational movement between the rotating hammer frame 30 and the anvil means 21. When this condition occurs, the camclutch means 32 of this invention operates automatically and periodically to axially displace the hammer means 31 appropriately to bring about its interfering engagement with and delivery of repeated impact blows to the striking faces 25 or 25' of the anvil means.

The hammer frame 30 (as seen best in FIGS. 1 and 2) constitutes the main support portion of the impact mechanism 15 and provides substantially the major mass portion thereof so as to function somewhat as a flywheel. The hammer frame also houses the hammer means 31 and the improved cam-clutch means 32.

With these purposes in mind it will be understood that the hammer frame is constructed substantially as a cylindrical cup-like member having a central longitudinal axis of rotation which is aligned coaxially with shaft 19, spindle 33, and anvil means 21 in the assembly of elements shown in FIGS. 1 and 2. The hammer frame 30 is preferably constructed as a unitary metal member with a central cup bore 35 opening inwardly of its one outer end 36, said end 36 being distinguished by a pair of diametrically opposed and wedge-shaped slotted openings 37, 37 (see FIG. 3) matingly receptive of diametrically opposed wedgeshaped arm sectors or portions 38, 38 of the hammer means 31. The opposite or inner end of the hammer frame is formed with a substantially cylindrical inset shoulder portion 39 and an axially projecting cylindrical hub portion 40 which is axially bored and internally splined for driving connection with the male splined end portion 20 of drive shaft 19. This provides positive driving connection between the hammer frame and the drive shaft. Rotational support for the hammer frame 30 is provided by suitable ball bearing assembly 41, concentrically surrounding and engaging the external surface of the cylindrical hub portion 40 thereon. The ball bearing means 41 in turn is mounted in and supported by the annular support frame 27 which also holds the shaft bearing 26 held by internal partitioning of the housing 18, as shown in FIGS. 1 and 2 of the drawings.

While normally the hammer means 31 is nested with in one end of the hammer frame 30 so that its projecting arm portions 38, 38 are slidingly journalled in the slotted opening 37, 37, such is intended to operably reciprocate periodically along the spindle 33 relative to the hammer frame for purposes of delivering a striking blow to the anvil means 21. In general, the hammer means 31 is formed with a substantially cylindrical main body portion 45 (see FIG. 3) from the opposite sides of which project the two arm portions 38, 38 thereof shaped substantially as arcuate segments or Wedges. Each of the arm portions 38, 38 further presents a pair of striking end faces 46 and 47, at its opposite ends, which are adapted to engage respectively opposing anvil faces 25 and 25' of the anvil means 21, as will be described more fully hereinafter.

As shown in FIG. 3 in particular, the segmental arm portions 38, 38 of the hammer means 31 project axially beyond the outer end face 48 of the hammer body portion 45 while the opposite end face 49 of the body portion 45 bears a pair of diametrically opposed and armately shaped, depending projections 50, 50*. Such projections extend axially outwardly of the end face 49 for driving engagement with the cam-clutch means 32 as will also be set forth in greater detail presently.

Body portion 45 of the hammer means 31 is further axially bored with a central axial opening 51 through which the spindle means 33 passes and which is of a diameter sufficient to receive, concentrically surround, and give bearing guidance to an axially extending cylindrical collar portion 52 associated with one cam element of the cam-clutch means 32, the details of which will be described later herein.

Both the anvil means 21 and the hammer means 31 are mounted concentrically about the spindle 33, as shown in FIGS. 1 and 2; the anvil means being rotatable with the spindle while the hammer means 31 rotates thereabout in response to its rotation with the hammer frame 30. The hammer means 31 is also arranged, as mentioned, to periodically reciprocate along the spindle 33 in response to the opposing operations of the cam-clutch means 32 and a return spring 53, the latter of which extends between a Washer 54 located adjacent face 48 of the hammer means and the adjacent surface 55 of an enlarged cylindrical head portion 56 formed at the outer end of the spindle means 33 (see FIGS. 1, 2 and 3).

As shown best in FIGS. 2 and 3, the spindle and anvil means are keyed together by means of pins 60, 60 which are received in matching opposing recesses 61 and 62 formed respectively in the exterior walls of the enlarged head portion 56 of the spindle and the interior walls of an axial blind bore opening 63 extending inwardly of the inner end 64 of the anvil member 21. This arrangement serves to lock together the spindle and anvil member while permitting the spindle to be inserted into the blind bore 63 along with the return spring 53, according to the assembly of parts illustrated in FIG. 2 for example. A single ball 65 is also disposed between the outer end of the spindle head portion 56 and a conical seat formed in the bottom end of the blind bore 63; said ball serving to align the spindle coaxially with the blind bore.

It will be recognized from the foregoing description that the spindle 33 and anvil member 21 are normally fixed together in assembly for conjoint rotation with the return spring means 53 normally acting to oppose movement of the hammer means 31 toward the anvil means and vice versa. The inner end of spindle 33 is similarly coupled to the clutch means 32 by means lockingly receptive of the male splined end portion 66 of the spindle means, while a second single ball 67 is prefer-ably disposed between the inner end of the spindle and an adjacent bearing plate 68 formed with a conical ball seat therefor and disposed in the bottom of the blind cup bore 35 of the hammer frame 30, substantially as shown in FIG. 2. One or more ball keys 69, 69 are also used between the male splined end portion 66 of the spindle and the walls of the splined central bore in one cam element of the cam-clutch means to insure proper operational alignment and interconnection of these parts as will now be set forth.

The cam-clutch means 32 uniquely comprises two disc like metal clutch cam elements suitably hardened or selected of a material having desired resistance to wear, and comprising an annular anvil cam element 70 and an annular hammer cam element 71 shown respectively in FIGS. 4 and 5 of the drawings. Basically these two cam elements are coaxially aligned in end-to-end opposing relationship on the spindle 33 for operation within the cup bore 35 of the hammer frame, and are so formed as to present on the opposing faces thereof cooperating, recessed cam track means shown herein as grooves for guiding a suitable ball follower, which in conjunction with a selected number of riser portions in the opposing cam track means, serves to effect periodic axial separation of the cam elements 70 and 71 in response to relative rotation therebetween.

The anvil cam element 70 (as seen best from FIGS. 1, 2 and 3) is disposed in the bottom of the cup bore 35 of the hammer frame, adjacent bearing plate 68 and is preferably formed as a substantially annular disc element having a cylindrical hub portion 72 at one end of its body portion 73. Hub portion 72 presents an external cylindrical surface which is engaged by a surrounding supporting ball bearing means 74 mounted in the bottom of the hammer frame cup bore 35. The hub and body portions '72 and 73 are also provided with an axially extending splined bore 75 adapted to receive and matingl-y engage with the male splined end portion 66 of the spindle means 33, as previously mentioned. Thus cam 7 0 and the spindle means 33 are locked together for conjoint rotational movement with the anvil means 21.

In addition to the central axial bore 75 of its hub portion 72, the main annular body portion 73 of cam 70 bears an enlarged central counterbore at 76 and a substantially annular recessed cam track means 77, formed inwardly of one outer end face or wall 78 thereof.

As shown particularly in FIG. 4 of the drawings, the recessed cam track means 77 includes a single node riser portion 79 which is symmetrical of its central axis and is rounded over or formed with a radius at its peak, as seen best in FIGS. 8-13, for rolling engagement with a single ball follower 88. The bail follower preferably has a radius slightly less than the radius of formation for the recessed track portion 77 so as to effect substantially tangential =line engagement with the cam track means. In normal circumstances the line of engagement between the ball follower means 80 and the cam track means 77 occur substantially at the bottom of the latters curvilinear groove of formation which desirably reduces frictional rolling engagement between the cam and cam follower to a minimum. 7

The hammer cam 71, as seen in FIGS. 3 and 5 in particular, is, like the anvil cam 70, formed with a substantially annular body portion from one end of which extends the axially projecting cylindrical hub portion 52 which, it will be recalled, fits within the central bore 51 of the hammer means 31. Contrary to the central bore opening 75 of anvil cam 78, the central bore 86 of the hammer cam is interiorly smooth for the passage of spindle means 33, as will be understood by examining FIGS. 1 and 2 of the drawings. Cam 71 also has a small annular hub portion 87 which projects axially outwardly or beyond the inner end face 88 of its body portion 85; such hub 87 being adapted to fit coaxially within the recessed counterbore 76 of the anvil cam 70, illustrated in FIG. 1.

End face 88 of the hammer cam, which opposes end face 78 of the anvil cam in assembly, includes a substantially annular recessed cam track means 89, formed to have substantially tangential line engagement with the ball follower 80 and distinguished by a single symmetrical riser node portion 90 along its annular course. The body portion of cam 71, throughout the major part of its circumference, is reduced in diameter over the outside diameter of the anvil cam so as to present an arcuate projecting circumferential ear portion 91 which affords connection of the hammer cam and the hammer means 31; such ear portion 91 being engaged at its ends by the depending or axially extending segmental lug projections 50, 50 of the hammer means. In this manner, rotation of the hammer means serves to drive the hammer cam rotatably therewith about the spindle 33 in response to rotation of the hammer frame. It will be understood also that the described connective system between the hammer means and the hammer cam provides a lost motion system, with the arcuate extent of the projecting ear portion 91 determining the operational positioning of the hammer means relative to the hammer cam 71 and more particularly the repositioning of the engaging portions 38 thereon with respect to the segments 24 of the anvil means. Thus, upon reversal of the drive motor, an operational phase shift takes place between the hammer means and the hammer cam to realign the striking segments of the hammer means to engage the reverse striking faces of the anvil means. In this functioning the arcuate extent of length of the projection 91 on the ham mer cam serves to properly align the hammer means so that faces 25 or 25' of the anvil striking segments are engaged by the hammer arm faces 46 or 47. Thus, for example, if on clockwise rotation of the drive motor and shaft 19 the striking surfaces 46, 46 of the hammer means are aligned to engage the striking anvil faces 25, 25 of the anvil means, upon reverse or counterclockwise rotation of the motor and shaft means, the opposite end faces 47, 47 of the hammer means will engage the opposite striking faces 25', 25 of the anvil means.

With special regard to the recessed cam track means 89 of the hammer cam 71, it is important to note that the same bears an increased depth over the cam track means 77 of the anvil cam. By way of example, with a cam follower ball diameter of 7 inch, track means 89 may be .210 inch deep as compared to a depth of .160 inch for track means 77. This relationship is brought out best in the developed representation of these two cam tracks as set forth in the drawing FIGS. 8, 10, 12 and 13. Additionally, the single node riser portion 90 of the hammer cam track means 89, unlike the radiused node 79 of the anvil cam, is developed to a sharp peak with greater length to its riser surfaces than that employed for the riser surfaces of the anvil cam node portion 79, although the slopes of such riser surfaces on both node portions are substantially the same. Node portion 90 is also of slightly greater depth than node portion 79; .200 inch from base to peak as compared with .150 inch for node portion 79 in the aforenoted example. These features, namely, increased depth of the cam track means 89 over the cam track 77; the increased length of riser surfaces and increased height from peak to base for cam riser portion 90 as compared to cam riser portion 79; plus the formation of a sharp peak on riser portion 90 as opposed to the rounded or radiused peak of riser portion 79, all serve to produce .positive and effective means preventing the ball follower means 80 from overriding the hammer cam riser portion 90. Thus in operation, while the single ball follower 80 rides partially up the slope .of riser portion 90, it preferentially rides up and over the more shallow and rounded off riser portion 79 of the anvil cam. In effect, therefore, the node portion 90 of the hammer cam serves as a positive means for moving and positioning the single ball follower along the opposing cam track means, @and relative to riser portion 79 of the anvil cam. This means that, for a given direction .of relative rotation between the two cam elements 70 and 71, the single ball follower is always positively located to one side of the cam node riser portion 90 of the hammer cam and positively moved thereby along track 77 so that it will engage and override the shallower, rounded-over cam node riser portion 79 of the anvil cam at the proper phase in the operating cycle for the camvclutch means. Thus, selected relative rotation between the two cam elements 70 and 71 positively produces desired axial separation thereof in proper preselected timing and sequence according to this invention.

It will also be understood that with the hereinabove described system for effectively preventing the overriding of the heightened cam node portion by the single ball follower means, the wear produced by the rolling engagement of the ball follower with the opposed cam track means always favors an increased wear of the cam riser portion 79 of the anvil cam. This of course enhances the operational functioning of the ball follower 80 to override only the riser portion of the anvil cam, there by maintaining required operational phase and proper positioning of parts necessary for the successful delivery of an impact blow to the anvil means in an impact wrench or like impact device.

Remembering the foregoing described relationship of parts which positively produces movement of the single ball follower 80 only over the riser portion of the anvil cam, it will be understood that when cam elements 70 and 71 each have but a single cam node riser, a single axial separation of such cams will occur each time the ball follower 8t) overrides the cam node riser portion 79 of the anvil cam. This single axial separation further occurs independently of the direction of rotation for the hammer cam, that is, whether clockwise or counterclockwise in response to the driving rotation of the motor means 17, and once for every full revolution of the hammer cam relative to the anvil cam.

It further will be recalled that one of the objectives of this invention is to provide a novel cam-clutch arrangement in which the frequency of axial separation and the attendant delivery of impact blows to a rotatable driven anvil mechanism is selectively variable. To this end a typical modified anvil cam, readily substitutable for the anvil cam 70, and capable of producing an increased frequency of axial separation between the hammer and anvil cams is designated generally by numeral in FIG. 6 of the drawing. Modified anvil cam 95 differs from the anvil cam 70 of FIG. 4 principally in the provision of a pair of cam node riser portions 96 and 97 formed like node portion 79 described above but disposed substantially diametrically opposite or apart along the length of the modified cam track means which is separated into two arcuate segments or portions 98, 98', as illustrated. With such a modified anvil cam 95, each full revolution of the hammer cam 71 of FIG. 5 relative thereto produces two axial separations-one for substantially each 180 of relative rotation between the hammer cam and the modified anvil camthereby to accomplish one instance of selected variation in impact frequency. Other similar modifications will readily occur to those versed in the art, as for example by providing a modified anvil cam having three or four node riser portions. While it is also possible to vary the number and spacing of the cam riser portions in the hammer cam, as a practical matter it has been found that a single node riser on the hammer cam coupled with selected variation of the number of risers on the anvil cam is satisfactory and dependable for varying cam separation frequency while maintaining desired operational positioning of the parts.

Turning now generally to the operation of the abovedescribed mechanism, reference is made particularly to FIGS. 1, 2, and 7 through 13 of the drawings. As shown in FIG. 1, the two cam elements 70 and 71 are in near contacting relationship with the single ball follower means 80 riding in their respective opposed cam track means 77 and 89. In this condition of operation the hammer means is fully retracted or withdrawn from its position of interfering engagement with the anvil means 21. In FIG. 2, on the other hand, full axial separation of the cam elements 70 and 71 is illustrated, such as occurs upon the delivery of an impact blow from the hammer means 31 to the anvil means 21. The exact sequential operation and particularly the relationship of the axial separation of the cam elements 70 and 71 in response to rotational driving of the hammer frame and hammer means will be understood best with study of the drawings FIGS. 7 through 13, as will now be described.

As shown in the perspective view (FIG. 7), hammer frame 30 is therein depicted rotating in a clockwise direction as viewed from its lefthand end, substantially at the start of a cam-separating cycle. In that condition the anvil cam 79 is positioned as depicted in FIG. 8 with the single ball follower 89 at the foot of the single cam node riser portion 79 thereof. Likewise, the single ball follower S9 resides substantially at the base of the single lengthened cam node riser portion 99 of the hammer cam; the latter being coupled to the hammer means 31 for rotation therewith relative to the anvil mans 21, spindle 33, and the anvil cam 70. With continued rotation in a clockwise direction from its FIG. 7 to its FIG. 9 position, the ball follower means 80 commences to rise along the anvil cam riser portion 79 as well as along the longer riser surface of hammer cam riser portion 90 (see FIG. 10). At that stage of operation slight axial separation of the hammer cam from the anvil has taken place to accordingly throw the hammer means 31 toward the anvil means 21 and to commence corresponding outward axial movement of the hammer means against the force of spring means 53. With continued like rotation of the hammer frame and hammer means from the positions thereof shown in FIG. 9, the hammer means 31 is eventually thrown axially outwardly its maximum extent. This relationship is particularly illustrated in FIGS. 11 and 12 of the drawings. In this operating condition the single ball follower 80 between the anvil and hammer cams 79 and 71, respectively, causes maximum separation of such two cams by riding over the rounded or radiused riser portion 79 of the anvil cam (see FIG. 12). As the ball follower 80 overrides the cam node riser portion 79 as aforesaid, it remains to one side of and is pushed along by the longer riser portion 9% on the hammer cam 71, and, in fact, never does override riser portion 99 due to the latters increased height over riser portion 79, coupled with its increased length of slope and its sharp peak, as above explained.

Immediately after the ball follower 89 passes dead center position over cam node riser portion 79, however, the condition illustrated in FIG. 13 occurs. As therein depicted, retraction of the hammer means with a rapid re turn of the hammer cam axially toward the anvil cam occurs, causing the ball follower 80 to ride down the slope of the anvil cam riser portion 79, advancing rapidly toward the base of the hammer cam riser portion 9%. This activity is so rapid in response to the urging of the spring means 53 as to cause the ball follower means to be effectively ejected from between the then opposing riser portions 79 and 99 (see FIG. 13), causing the ball follower to advance along and between the opposing cam track portions in the direction of advance or rotational movement of the hammer. This advancing movement is indicated by dotted line position 80 for the ball follower in FIG. 13. Such advancing movement of the ball follower enhances rapid return activity of the two cam plates to their battery positions for the repetition of the operational separating cycle as above described.

It will be understood that regardless of the amount of travel or advance the ball follower 80 makes along the opposing cam track means with return movement or retraction of the hammer means 31, the cam node riser portion 90 eventually picks up the ball follower in response to and with the rotational movement of the hammer cam, the hammer 'body, and the hammer means, so as to positively advance the same into position for again initiating the rise of the ball follower along the cam node riser portion 79 of the anvil cam, as set forth in FIG. 8. Thus a positive means is provided in the improved cam-clutch means of this invention for insuring that the ball follower will be maintained in proper phase relationship and be positioned readily to produce 19 the desired axial separation of the cam can elements for delivery of an impact blow to the anvil means. This action, of course, is also accorded to the selected operating frequency for the impact mechanism.

In a similar manner, it reverse rotational operation of the impact mechanism is desired, counterclockwise rotation of motor 17 produces a corresponding axial separation of the cam elements, since the riser portions thereof are symmetrical. In such case, the ball follower means is engaged and picked up by the opposie side or riser surface of the hammer cam node riser portion from that shown in the successive operational illustrations (FIGS. 7 through 13). In such reverse operation, again there is positive pickup of the ball follower and positive positioning of the same by riser portion 90 to insure its overriding of cam node riser 79 according to the required operational timing of the impact mechanism.

As stated previously, with a single node riser 79, as on the anvil cam 79 of FIG. 4, axial separation of anvil and hammer cams occurs for each approximately 360 of relative rotation between the two cam elements. If a modified anvil cam having a pair of node risers, such as modified cam of FIG. 6, is substituted for cam 70, axial separation of the modified anvil cam and the hammer cam 71 of FIG. 5 will occur for substantially each 180 of relative rotation therebetween.

The aforesdescribed operation of the two cam elements to cause axial separation thereof is effectively harnessed by the mechanism of this invention to produce the gradual axial displacement and quick return of the hammer means 31 as set out in the drawing FIGS. 7, 9 and 11.

With regard to such axial throw of the hammer means, it will be noted that during clockwise rotation of the hammer frame the striking surfaces 416, 46 of the hammer arm portions 38 effectively engage or deliver impact blows to the striking anvil means 21. Conversely, during counterclockwise rotation of the hammer frame the opposite end faces 47, 47 of the hammer arm portion engage the striking faces 25', 25 of the anvil means. In both instances, the radial alignment of the engaging striking faces 46 and 25, or 47 and 25, of the hammer and anvil means, respectively, is such as to produce substantially full facial engagement therebetween at the point of impact delivery. Also, upon reversal of the rotational operation of the hammer frame '30, the lost motion connection provided between the hammer means 31 and the hammer cam 71 permits a relative movement or phase shift between such parts to permit the hammer means to be raised on the reverse side of the anvil arm portions for engagement between the reverse striking surfaces 25', 25' of the hammer arms and anvil arm portions. Thereafter the described mechanical lockup between the hammer means and the hammer cam produces conjoint rotation of the hammer means and hammer cam element in response to continued rotational driving action of drive shaft 19.

It is intended with the scope of this invention that each of the cam elements 70 and 71, and more particularly the anvil cam element 70, may selectively include one, two, or more riser portions to produce a desired corresponding frequency of delivering impact to the anvil means as previously related. Additionally it is contemplated that each of the cam elements 70 and 71 may bear an unlike number of riser portions respectively in their recessed cam grooves so as to provide a further selective variation of operating frequency or delivering of blows to the anvil means. Thus the versatility of the unique cam-clutch means of this invention will be recognized as fully capable of producing a wide selection of operating characteristics for an impact tool with which it is associated.

From the foregoing it is believed that the structural and operational aspaces and features of the improved mechanism of this invention will be readily recognized by those familiar with the art and that it will be appreciated that numerous changes, modifications and substitutions of equivalents may be made therein without necessarily departing from its spirit and scope. Further, while I have herein described my invention as it appears in a preferred embodiment thereof, illustrated in the accompanying drawings, it is not my intention that the invention be limited by the particulars of the foregoing description except as may appear in the following appended claims.

I claim:

1. An improved impact mechanism for use in rotary impact tools and adapted to be rotatably driven by motor means todeliver torque impact to a driven tool element comprising, in combination, a rotatably supported hammer frame having driving connection with the motor means and formed with diametrically opposed recesses in its one end, hammer means having radially extending arm portions, each with a striking portion, nested in the said recesses of the hammer frame for coaxial rotation therewith, a spindle member extending coaxially through said hammer means and having one end portion projecting axially outwardly of said hammer frame and hammer means, anvil means fastened to the said one end portion of said spindle means for connection with tool elements to be driven and including radially extending arm portions disposed adjacent said hammer means and presenting striking surfaces for impact engagement by the said striking portions of said hammer means, spring means normally biasing said hammer means and anvil means apart, and rotatable cam means mounted in said hammer frame and comprising a pair of annular cam elements, each arranged concentrically of said spindle means and including riser portions, a follower means cooperating with said cam elements for effecting axial separation of said cam elements and the displacement of said hammer means against the force of said spring means in response to relative rotation between said cam elements, the cam riser portions on one of said cam elements being formed to prevent the overriding thereof by said follower means, and means connecting one of said cam elements to said spindle means for rotational movement therewith and the other of said cam elements to said hammer means for movement therewith to effect the said relative rotation therebetween.

2. The combination as set forth in claim 1 in which said cam elements have their riser portions cooperatively arranged with said follower means between opposing end faces thereof to operate at preselected points of relative rotation between said cam elements to effect axial separation thereof in response to both clockwise and counterclockwise rotation of said hammer frame.

3. The combination as set forth in claim 1 wherein the said cam elements have their cooperating riser portions arranged and formed to effect their axial separation once for each revolution of said hammer frame.

4. The combination as set forth in claim 1 wherein said cam elements have their cooperating riser portions arranged and formed to effect axial separation of said elements once for each one-half revolution of said hammer frame.

5. An improved impact mechanism for use in rotary impact tools and adapted to be rotatably driven by a reversible motor means to deliver torque impact to a driven tool element comprising in combination, a rotatably supported hammer frame having driving connection with the motor means and formed with a central blind cup bore and diametrically opposed recesses opening inwardly of its one end, hammer means having radially extending arm portions each with a striking portion adjacent its periphery nested in the said recesses of the hammer frame whereby said hammer frame and hammer means are conjointly rotatable with the motor means, a spindle means extending coaxially of said cup bore and hammer means and having one end portion projecting axially outwardly of said hammer frame and hammer means,

rotatable driven anvil means mounted on said one end portion of said spindle means for connection with tool elements to be driven and including radially extending arm portions disposed adjacent said hammer means and presenting striking surface portions for impact engagement with the striking portions of said hammer arm portions, spring means normally biasing said hammer means away from said anvil means, cam-clutch means mounted in said cup bore and including two annular cam elements mounted in coaxial adjacency on said spindle and formed with registeringly opposed recessed cam tracks in their adjacent end faces receptive of a single ball follower means which rolls therein, said cam tracks including opposing cam node riser portions having sloping riser surfaces with the riser portion in one of said cam tracks having longer riser surfaces than the riser portion in said other cam track, one of said cam elements being connected to said hammer means and the other thereof to said spindle means whereby rotation of said hammer means with said hammer frame produces relative rotation between said cam elements to cause said ball follower means to be carried along said track means and override the said riser portion having the shorter riser surfaces to thereby axially separate said cam elements, the axial separation of said cam elements compressing said spring means and moving said hammer means axially toward said anvil means to effect impact engagement between their respective said striking portions and striking surfaces.

6. The combination as set forth in claim 5 wherein said one cam element has lost motion connection with said hammer means to cause the latter to rotate relative to said one cam element and engage striking surface portions on opposite sides of the said arm portions on said anvil means during clockwise and counterclockwise rotation of said hammer means.

7. In an impact mechanism an improved cam-clutch means comprising, a pair of disc-like cam elements arranged in coaxial end-to-end adjacency and having cooperating cam portions between the opposing end faces thereof, said cam portion including symmetrical node riser means, each with inclined riser surfaces, the riser surfaces on one of said node means being longer than the riser surfaces on the other said node means, means normally biasing said cam elements into contacting adjacency, and means for effecting relative rotation of said cam elements to produce the periodic axial separation thereof against the action of said biasing means when the said riser means thereon are moved past one another.

8. In an impact mechanism an improved cam-clutch means comprising, two disc-like cam elements arranged in coaxial end-to-end adjacency, said cam elements having cooperating cam portions each with riser means between the adjacently opposed faces thereof, cam follower means engaging and movable along said cam portions, means normally biasing said cam elements into contacting adjacency, means for effecting relative rotation of said two cam elements to produce their periodic axial separation against the effect of said biasing means when the riser portions thereof are moved into opposing relationship with the said cam follower means therebetween, and means for positively aligning said follower means between said riser portions in response to preselected rel ative rotation of said cam elements.

9. In an impact mechanism an improved cam-clutch means for producing periodic reciprocating motion comprising, a pair of disc-like cam elements arranged in coaxial end-to-end adjacency with the opposing and faces thereof having opposed recessed cam tracks, cam follower means movable in the said cam tracks between said cam elements, riser means in each of said cam tracks, and means for rotating said cam elements relative to one another whereby said cam follower means is caused periodically to engage the riser means of opposing cam tracks therein to axially separate said cam elements, with the 13 said riser means of one of said cam elements being formed to prevent the overriding thereof by said follower means, thereby to positively position said follower means to engage the riser means in the other said cam element.

10. In an impact mechanism an improved cam-clutch means between a rotatable drive means and a periodically impacted rotatable driven member comprising, a pair of annular cam elements arranged in coaxial end-to-end adjacency with one of said cam elements being rotatable with said driven means and the other thereof rotatable with said drive means, said cam elements having cooperating cam portions between the adjacently opposed end faces thereof comprising cam tracks formed inwardly of said faces and each including at least one node riser portion, and ball follower means in said cam tracks adapted periodically to engage the said riser portions and override the riser portions in one of said cam tracks to axially separate said cam elements upon preselected relative rotation therebetween.

11. In an impact mechanism an improved rotatable clutch means between rotatable drive and driven means comprising, two annular cam elements arranged in endto-end coaxial adjacency with one cam element being rotatable relative to the other, one moving with the drive means and the other thereof with the driven means, annular cam track means formed in adjacent opposing faces of said cam elements with each cam track means including at least one node riser portion, the cam track means being disposed in opposing registration, and a single ball follower means movable along the opposing cam track means whereby relative rotation between said cam elements causes the ball follower means to simultaneously engage the said riser portions and override the same to separate said cam elements; one of said cam tracks being deeper than the other, with the said riser portion therein formed with a pointed peak and elongated sloping sides, while the riser portion of said other cam track is formed with a radiused peak and shorter sloping sides so that said ball follower normally overrides only the riser portion with the shorter sloping sides.

12. An improved impact mechanism for use in rotary impact tools and adapted to be rotatably driven by reversible motor means to periodically deliver torque impact to a driven tool element comprising, rotatably driven hammer means having extending arm portions, a spindle member extending coaxially of said hammer means and guiding the same for axial reciprocating movement, anvil means mounted on said spindle means for connection with tool elements to be impacted and including arm por tions disposed for impact engagement with the arm portions of said hammer means, means normally biasing said hammer and anvil means apart, and a reversible camclutch means mounted adjacent said hammer means for rotation therewith and operable to rotate said anvil means and periodically eifect axial movement of said hammer means toward said anvil means to deliver impact bloWs to said anvil means when the latter encounters sufiicient torque resistance to rotate said spindle means either clockwise or counterclockwise relative to said hammer means, said cam-clutch means comprising only two rotatable cam elements, one rotatable with said hammer means and the other rotatable with said anvil means, a cam node riser portion formed on one of said cam elements, and a cam follower means driven by the other of said cam elements for periodically engaging said riser portion to override the same and effect axial separation of said cam ele ments and responsive axial movement of said hammer means; the said biasing means rapidly reversing said axial movement of said hammer means immediately after said follower means overrides the high point of said riser means.

13. In an impact mechanism an improved rotatable clutch means operable between rotatable drive and driven means comprising, two annular cam elements arranged in end-to-end coaxial adjacency with one cam element being rotatable relative to the other, the said one cam element moving with the drive means and the other cam element moving With the driven means, annular cam track means formed in adjacent opposin'g faces of said two cam elements with each track means including at least one node riser portion, a single ball follower means movable along the opposing said cam track means whereby relative rotation between said cam elements causes the said ball follower means to periodically engage opposing said riser portions to override the same and separate said cam elements, the said riser portion in one of said cam elements being formed with a longer riser slope than the riser portion of the other cam element thereby to cause the said ball follower means to preferably override only the latter riser portion.

References Cited in the file of this patent UNITED STATES PATENTS 2,049,273 Pott July 28, 1936 2,160,150 Jimerson et al May 30, 1939 2,539,678 Thomas Ian. 30, 1951 2,881,884 Amtsberg Apr. 14, 1959 2,907,240 Schwenk et al. Oct. 6, 1959 FOREIGN PATENTS 738,951 Great Britain Oct. 19, 1955 1,057,422 France Oct. 28, 1953 i UNITED STATES PATENT @FFICE CERTIFICATE 0F CORRECTION Patent No. 3,053360 September ll,.l962

Jens Axel W. Madsen It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below Column l line 10, after "impact" strike out the comma; I

column 9, line 75 for "readily' read ready column 10, L line 3 for "accorded" read according line 36, after "striking" insert anvil faces 25, 25 of the line .38 i for portion" read portions Signed and sealed this 19th day of February 1963'.

(SEAL) Attest:

ESTON c, JOHNSON DAVID L. LADD Attesting Officer Commissioner of Patents 

